Electric soldering-iron.



No. 731,838. PATENTED JUNE 23, 1903.

I J. 1. AYER.

ELECTRIC SOLDERING IRON.

APPLICATION FILED MAR. 5, 1902.

N0 MODEL.

, UNITED STATES Patented June 23, 1903.

PATENT OFFICE.

JAMES I. AYER, OF MALDEN, MASSACHUSETTS, ASSIG-NOR TO SIMPLEX ELECTRICHEATING COMPANY, OF BOSTON, MASSACHUSETTS, A COR- PORATION OFMASSACHUSETTS.

ELECTRIC SOLDERlNG-IRON.

SPECIFICATION forming part of Letters Patent N 0. 731,838, dated June23, 1903.

Application filed March 5, 1902.

To all whom it may concern.-

Be it known that I, JAMES I. AYER, a citizen of the United States,residing at Malden, county of Middlesex, State of Massachusetts, haveinvented an Improvement in Electric Soldering-Irons, of which thefollowing description, in connection with the accompanying drawings, isa specification, like letters on the drawings representing like parts.

My invention is an electric soldering-iron, the principal objectsthereof being the provision of increased heat effectiveness and theprovision of increased life or durability.

Soldering irons must be comparatively small and are required to be ofprescribed general shape, as Well as size, and it is also desirable thatthey should have minimum weight and that the heat should not be wastedand should be confined to the active end or operative region of theiron, and ac-. cordingly it is the purpose of my invention to attainthese ends.

In carrying out my invention I provide a heat-convector of specialconstruction which cooperates with a soldering-tip at one end and with aheat-generator toward its other end and is surrounded by heatequalizing, and retaining means, including a special casing or shell.

The constructional details and other advantages of my invention will bemore fully pointed out in the course of the following description,reference being had to the accompanying drawings, in which I haveillustrated a preferred embodiment of my invention.

In the drawings, Figure 1 is a perspective view of a detail constructedaccording to my invention. Fig. 2 is a longitudinal sectional viewthereof. Fig. 3 shows the core and adjacent parts in side elevation.Fig. 4 is an endelevation thereof.

It will be understood that the handle end a of the tool may be of anyusual or desired construction, and accordingly I have not shown and willnot describe details thereof.

My invention relates more directly to the core and the adjacent andconnected parts.

The core is composed of highly-conductive material and comparativelylarge size, being Serial No. 96,795. (No model.)

The shoulengagement therewith throughout as large a cont-acting area aspossible, gives free direct transmission of heat from the core to thetip.

It is necessary in a soldering-iron that the tip should be capable ofextended use, and hence it must have considerable mass, and yet as, inspite of this fact, it will quickly wear out I make it removable, so asto re duce toa minimum the cost of use of the electric soldering-iron,the removability permitting all the expensive portion of the tool toremain permanently with the handle.

The construction of core gives a large contact-surface where the tip isjoined and also gives a large capacity for the transmission of heat byconduction, which, as is well known, is far more rapid than any othermeans of transmission and gives a continuous metallic conductor of largeconducting capacity which tends to concentrate all the heat of theelectric heat-generator at and toward the soldering-point c. I

The heat-generator may be of any construction adapted to the purpose,and for convenience I have shown the conventional coil of fine wire,which receives its current from circuit-wires d d.

All the constructional details of my invention conspire to securing thegreatest amount of heat with the least possible number of turns of theresistance-wire, from one to three layers (1 of the coil being entirelysufficient for the ordinary iron with a comparatively short core, theselayers being herein shown as separated from each other by micainsulators (2 As already intimated, a tool of this kind must be limitedin size and weight, and yet there must be a concentration of ample heatat the tip end, and while increasing the diameter of the core enables meto provide a heatgenerator of thin cross-section sufficient to producethe requisite heat by bringing the generator into closer contact withthe conducting material of the core and the large mass of the latteralso affords a free path by conduction for the heat to the tip Iaccomplish this without increasing the weight, and at the same time Iprovide means for directing the heat toward the tip end and preventingthe same from passing as freely in the opposite direction by making theupper or righthand end of the core more or less hollow, as indicated atN, where I have shown a conical recess. This avoids increasing theweight while providing relatively large mass of conducting material, asalready explained, the core being relatively thin at its upper end,where it receives the heat of the first few turns of resistance-coil,and grows gradually thicker or greater in mass as it approaches thesoldering-point end and is called upon to receive and conduct away theincreasing or accumulating supply of heat, which becomes greater andgreater as that end of the core is approached.

Cooperating with the foregoing in conserving the heat for practical useI provide an.

air-chamber 6 around the core, this air-chamber being inclosed by acasingf, which constitutes the upper portion of the external part of thesoldering-iron, and by a diaphragm or head g, of poor or non conductingmaterial, preferably in the form of a mica washer, which extendstransversely of the jacket f, into peripheral contact therewith, and issecured against the end of the core by any suitable means, as byaclamping-ring g and setscrew 9 This construction I regard as of muchvalue. 1 have also shown the parts held in place by dowels g and thescrew 9 as screwing into a plug 9 The closed airchamber tends to preventthe loss of heat by convection-currents or air circulation, which wouldoccur if it were nota closed chamber, and the thin casingf, which issecured to the shoulder 17 at f and carries the handle atf gives aminimum tendency to conduct heat longitudinally away from the superiorconductor provided in the large mass of conductive material at thesoldering end of the tool.

Preferably the casing or shellfis secured to the core in such a manneras to prevent a ready conduction of heat from the core to the casing andprevent access of soldering-acids to the electric heat-generator, theconstruction herein shown comprising a groove lined with asbestos ormica or filled with non-conducting cement or other material f calculatedto withstand the high temperature and the action of strong acid withoutbeing easily destroyed. This performs the threefold office ofpreventingcontact of the shell with the metal of the core, securing theshell and the connected handle, &c., rigidly in place, and preventingthe entrance of acid used in soldering.

The shell is composed of material, preferably thin metal, having slowconductive or heat-transmitting capacity in the direction of its length,but good heat-transmitting capacity transversely of its length. Thisconstruction prevents automatically the tool from destroying itself byan undue increase in temperature while idle.

As'is well known, the work required of a soldering-iron is quiteintermittent, and yet the current is usually kept the same under allconditions, so that there must be a sufficieut current to render thesoldering-iron effective while being used, and therefore when not in useif the heat were confined absolutely the temperature would riseexcessively, and it becomes desirable, therefore, to provide aninclosing medium which will freely permit the radiationt'. 6.,transverse passage of heat-from the core whenever the heat thus rises.

When the iron is in use, the energy is utilized ,in work; but during thelonger or shorter periods of time when the current-supply is continuedbut the iron is idle all of the heat generated must be disposed 'ofentirely by radiation from the exposed surfaces. The loss of heat underthe latter conditions is usually much less rapid than under conditionsof work, and accordingly I provide the special construction of shellwhich facilitates radiation or transverse disposal of the heat andpermits the degree of radiation to increase with the rise intemperature. The radiation losses except at high temperatures are notmaterialas, for instance, at 400 or 500 Fahrenheit radiant heat does notpenetrate a great distance-and hence the airjacket conserves the heat atthe lower temperatures and prevents loss, except to a very feebleamount; but as the temperature increases the radiant heat becomes suchthat it readily penetrates the thin conductive casing and escapes freelyto the outside atmosphere. In other Words, this feature of my inventionprovides a shell which permits free radiation of heat at hightemperatures when the iron is doing no work; but when the iron is atwork and heat would naturally be lost by longitudinal conduction fromthe shoulder I) along the shell or casing the insulated andnon-conductive character of the construction prevents such loss. In amanner this thin shell is automatic because as the temperature rises itrelieves the iron with sufficient rapidity to keep down very materiallythe temperature, while at working temperatures the losses therefrom arecomparatively slight. The core and its shoulder being one piece and thejoint with the shell being nonconducting and the joint with the tipbeing such as to permit the best and freest conduction cooperate withthe other features already explained in bringing the greatest efficiencyof heat effects at the tip of the tool.

The construction above explained makes it entirely feasible to operatethe heater with a comparatively low temperature in the resistance-wiresbecause of the few turns of wire,

one over the other, resulting in close proximity of all wires to thecore, and also because the core is of comparatively large mass and highconductivity, which rapidly conducts heat therefrom to the tip 0. Thesetwo features I regard as of great importance in my inventionnamely, theconstruction which permits the heat-generator to operate at a lowtemperature, whereby the life of the heater is increased, and theprovision of means for freely taking the heat away from the wire by thecore and easily conducting it to the work, whereby the losses of heatare reduced to a minimum and the efficiency of the tool is increased.

Without entering more fully upon the advantages of my invention I wishit understood that I do not limit myself to the constructional detailsherein explained otherwise than as expressed in the claims, inasm nch asmany changes and modifications may be resorted to without departing fromthe spirit and scope of my invention.

Having described my invention, what I- claim as new, and desire tosecure by Letters Patent of the United States, is

1. Asoldering-iron, comprising an electric heat-generating coil ofsubstantially uniform thickness, or number of turns, from end to end, acore therefor of substantially uniform external diameter from end toend, and soldering-tip, said core being provided with increased masstoward the end carrying said soldering-tip by means of a tapering cavitywith the apex pointing toward said solderingtip end.

2. Asoldering-iron, comprising an electric heat-generator, a coretherefor and solderingtip, said soldering-tip being carried at one endof said core, the core, excepting adjacent said tip, and theheat-generator being surrounded by an air-chamber, and a mica barriersupporting said casing out of contact with the heat-generator.

3. A soldering-iron, comprising an electric heat-generator, a coretherefor and soldering-tip, a casing surrounding and insulated from saidcore having large capacity for transverse heat transmission and smallcapacity for longitudinal conduction, and a diaphragm or barrier g ofpoor conducting material extending in peripheral contact with saidjacket or casing and forming with the latter a deadair chamber aboutsaid coil and core.

at. A soldering-iron, comprising a core of high conductive materialhaving a reduced upper portion and a radial shoulder adjacent itseffective end, a soldering-tip therefor, an electric heat-generatormounted on said reduced portion, a thin casing secured to said shoulderand inclosing said resistance-coil, having a free air-space between thelatter and said casing, and a washer or diaphragm of poor conductingmaterial carried at the upper end of said core and extending radiallyinto peripheral contact with said casing.

5. A soldering-iron, comprising an electric heat-generator, asoldering-tip, means for conveyin g the heat from said generator to saidtip, and a casing electrically insulated from said heat-generator andtip and inclosing said heatgenerator, said casing having large capacityfor transverse heat transmission and small capacity forlongitudinalconduction,and having a free air-space separating the same from saidheat-generator.

6. A soldering-iron, comprising an electric heat-generator, asoldering-tip, means for conveying the heat from said generator to saidtip, and a casing electrically insulated from the heat-generator andinclosing said electric heat-generator, out of contact therewith, andsecured in place by a heat-insulation joint. I

7. In a soldering-iron, an electric heat-generator, heat-conveyingmeans, a casing, and means, including a groove in said heat-conveyingmeans lined with non-heat-conductin g material, for retaining said casinIn testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

.TAS. LAYER.

Witnesses:

DORA A. PROCTOR, JOSEPH V. LATOUR.

